A phenomenological model for the responses of auditory-nerve fibers: I. Nonlinear tuning with compression and suppression

A phenomenological model was developed to describe responses of high-sponta neous-rate auditory-nerve (AN) fibers, including several nonlinear response properties. Level-dependent gain (compression), bandwidth, and phase prope rties were implemented with a control path that varied the gain and bandwid th of tuning in the signal-path filter. By making the bandwidth of the cont rol path broad with respect to the signal path, the wide frequency range of two-tone suppression was included. By making the control-path filter level dependent and tuned to a frequency slightly higher than the signal-path fi lter, other properties of two-tone suppression were also included. These pr operties included the asymmetrical growth of suppression above and below th e characteristic frequency and the frequency offset of the suppression tuni ng curve with respect to the excitatory tuning curve. The implementation of this model represents a relatively simple phenomenological description of a single mechanism that underlies several important nonlinear response prop erties of AN fibers. The model provides a tool for studying the roles of th ese nonlinearities in the encoding of simple and complex sounds in the resp onses of populations of AN fibers. (C) 2001 Acoustical Society of America.